The present invention relates to a docking unit that is to be coupled with a portable computer to expand the functions of the portable computer. More particularly, the present invention pertains to a docking unit for a portable computer with which, when employed by a plurality of users, absolute security can be maintained.
As a consequence of current developments in technology, various types of personal computers, such as desktop and notebook computers, have been developed and are available on the market. Of these computers, the notebook computers are battery-operable personal computers for which portability is a design consideration.
Since compact size and light weight are important notebook computer features, expanding these computers by adding peripheral devices internally is not practicable because no extra space is available, and device expansion that is accomplished by merely using a PC card can not sometimes provide a viable alternative. Furthermore, as the exterior dimensions of a notebook computer ensure but a small surface area, only a very limited number of bus slots can be provided. Thus, while it is not unusual for desktop computers to have ten or more bus slots, ordinarily no bus slots, or one or two at the most, are provided for laptop and notebook computers. And since portability is the most important feature for a notebook computer, having to attach or detach a cable (e.g., a printer cable, a monitor cable, a communication cable) each time the notebook computer is used, whether in or outside an office, is a very complicated task that adversely affects the usability of the unit.
The employment of a so-called "docking station" (also called an "expansion box" or an "expansion unit"), when a notebook computer is used in an office, makes it possible to provide with a notebook computer the same working environment as that provided with a desktop computer, while at the same time having no adverse affect on portability. The primary functions of a docking station are "port replication" and "bus expansion". Port replication function is realized by providing a docking station having connection ports for notebook computer expansion. In other words, when a cable has been connected to each port of a docking station in advance, a user need only dock a notebook computer in the docking station to immediately secure the use of a printer, an external monitor, and a network. From the point of view that all cable connections are managed by the docking station, the port replication function is also called a "cable management function". The bus expansion function is realized by a docking station possessing the capability to expand the bus in a notebook computer, and having at least one bus slot. By docking a notebook computer in a docking station, it is possible for a user to employ desired adaptor cards and devices via the docking station. In other words, no special limitations are placed on the user of a notebook computer.
Docking stations are disclosed in, for example, the specifications for Japanese Patent Application No. Hei 05-181593 (Internal docket No.: JA9-93-027), and in Japanese Patent Application No. Hei 06-134124 (Internal docket No.: JA9-94-030), both of which are owned in common with the present invention.
FIG. 21 of the accompanying drawings shows a typical notebook computer 100 and docking station 200. At the rear of the notebook computer 100, a connector (not shown, which is hereinafter referred to as a "docking connector") is provided. The docking connector generally includes several tens to several hundreds of connector pins, with each connector pin being assigned for a port signal line and a bus signal line in the notebook computer 100. The bus that the notebook computer 100 allocates for the docking connector (i.e., the bus for which expansion is desired) is ordinarily an ISA (Industry Standard Architecture) bus, which is an input and output bus. This is because the ISA bus has long been the popular standard in this field and there are thus legacy assets that can be inherited, such as ISA devices and ISA applications. In addition, among some of the latest notebook computers, instead of an ISA bus, a PCI (Peripheral Component Interconnect) bus, which is positioned as a local bus for a CPU, is assigned to a docking connector, i.e., the PCI bus is expanded. This seems to have occurred for the following reasons: the number of devices, such as graphics and PC cards, that require high speed data transfer has increased; expansion of the PCI bus is easy since a number of devices can be connected to a single PCI bus; and a bus can be electrically, stably expanded by means of a bridge circuit.
A PC card, that conforms to the preceding specifications, can be inserted into a PC card slot provided on the side of the notebook computer 100, or into a PC card slot provided on the side of the docking station 200. The insertion and removal of the PC card can be performed as desired.
The docking station 200 comprises a main body that incorporates electric circuitry; a mounting portion whereat the notebook computer 100 is mounted on the top of the main body; and a projection portion that projects upward from the rear end of the mounting portion. A connector is provided on the front face of the projection portion to engage a docking connector that is provided on the rear face of the notebook computer 100. The surface of the connector may be covered with a lid that is freely opened and closed in order to protect the connector when it is not in use. A pair of linear protrusions are so formed along both sides of the mounting portion that a notebook computer is guided along them as it is being mounted.
The configurations of docking stations vary, and they range from relatively small ones that have only a port replication function, to relatively large ones that can afford to provide a plurality of storage spaces (also called "media bays") in which fixed or detachable memory devices (HDDs, FDDs, CD-ROM drives, etc.) can be mounted, or that can accommodate a plurality of adaptor cards.
These docking stations are used in accordance with the users' needs, i.e., they are individually employed for the purpose of expanding the availability of peripheral devices for individual notebook computers, and are employed in common by a plurality of users for the purpose of expanding their notebook computers' peripheral environment.
For individual use (single user mode), the notebook computer of a user must be securely fixed to a docking station to protect it from theft. For this purpose, a key is used to secure the notebook computer in the docking station and to inhibit the extraction of PC cards. Then, the key is extracted and kept in a secure area so as to protect the notebook computer and the PC cards from theft.
When a docking station is to be employed by a plurality of users (multi-user mode), however, because each user must have a key, notebook computer protection that requires the use of a key is inconvenient, and the management procedures involved are complicated. When a docking station is used in common, the protection provided by using a key to secure a notebook computer in a docking station is not required, and once a user has completed an operation with a notebook computer docked in the docking station, the user can merely remove the notebook computer from the docking station. Nevertheless, as PC cards that are provided with a docking station are used in common, normally they should not be removed and must therefore be constantly protected from theft.
Conventional docking stations, however, do not completely provide the above described protection. In particular, there are no docking stations that afford the protection required for both the single user mode and the multi-user mode.